It is well known in the art that the above mentioned syntheses of Cimetidine and related drugs require the use, as intermediate, of MHI of high purity (not less than 97% assay), because the presence of excessive amounts of impurities adversely affects the quality of the subsequent intermediates prepared from the MHI and of the Cimetidine end-product.
One of the main impurities present in commercial MHI or its hydrochloride salt is 2,5-di(hydroxymethyl)-4-methylimidazole (hereinafter "DMHI") which is formed as a byproduct in the hydroxymethylation of 4-methylimidazole (hereinafter "MI"). Other impurities are unchanged MI and imidazole which usually contaminates the MI starting material.
The object of the present invention is to provide an improved process for the manufacture of high quality MHI including only minimal amounts of the above mentioned impurities which process should have the further advantage of providing high yields of said product while requiring only comparatively simple and convenient work-up procedures.